How do SGARs work?

SGARs (Second-Generation Anticoagulant Rodenticides) are a type of poison used to control rodents like rats and mice. They work by interfering with the rodent's ability to clot blood, ultimately causing them to bleed internally and die.

How blood normally clots

Our bodies (and animals) need blood to clot when we get a cut or injury, so we don’t bleed to death. There are certain proteins in the blood that help it clot, and these proteins depend on vitamin K to work properly.

What SGARs do

SGARs, like brodifacoum, bromadiolone, and others, stop the body from using vitamin K. Without vitamin K, the blood can't clot properly, so the rodent starts to bleed internally.

Over time, the rodent loses so much blood that it dies, usually a few days after eating the poison. This delayed effect means the rodent doesn't immediately associate the poison with feeling sick, which makes it more likely to eat the poison.

Why are they used

SGARs are very potent and work even in small doses. Plus, because they are toxic over several days, a rodent can ingest multiple doses before showing any signs of illness, which increases the likelihood that the poison will work before the rodent gets suspicious and stops eating.

Because of this they can also pose a risk to non-target animals, like pets or wildlife, if they accidentally consume the poison.

Why Are SGARs Dangerous to wildlife, pets, and children?

SGARs (second-generation anticoagulant rodenticides) are dangerous to wildlife for several reasons, and this risk extends beyond just professional pest control specialists to anyone who might encounter them in the environment. Here's why they pose a significant threat.

Secondary Poisoning

SGARs work by preventing blood clotting, which ultimately causes internal bleeding and death in rodents. When predators or scavengers (like owls, hawks, foxes, or even pets like dogs and cats) consume rodents that have ingested SGARs, they can also be poisoned. This phenomenon is called secondary poisoning. Even if the predator eats a rodent that isn't dead yet, the rodent could still have a lethal dose of the poison in its system, which can be passed up the food chain.

Bioaccumulation

SGARs are persistent in the environment and can accumulate in the bodies of animals over time. Unlike first-generation rodenticides, which break down relatively quickly, SGARs have a long half-life in the liver, meaning they can stay in an animal's system and continue to have toxic effects. This leads to the gradual buildup of toxins in both predators and prey.

Wide Range of Affected Species

SGARs are not selective in the animals they can harm. While they are designed to target rodents, they can affect virtually any animal that consumes a poisoned rodent. This includes non-target species like birds of prey, mammals, and even amphibians and reptiles that may ingest poisoned rodents or contaminated water.

Delayed Effects

The effects of SGAR poisoning can be delayed, sometimes taking days or even weeks to manifest. This makes it harder for people to spot the problem early, allowing the toxin to spread and impact a wider range of wildlife. For example, an animal may eat a poisoned rodent, then suffer from internal bleeding and die days or weeks later, before people notice any unusual behavior.

Threat to Ecosystems

Because SGARs can affect top predators and disrupt food chains, they can harm entire ecosystems. Predators that consume poisoned animals may experience reduced reproductive success, weakened populations, or even death, which can have cascading effects on the balance of species in that area.

Impact on Domestic Pets

Pets like dogs and cats can also be affected if they ingest SGARs directly or consume poisoned rodents. This is particularly dangerous because pets may not show symptoms immediately. Without prompt treatment, SGAR poisoning can be fatal.

Challenges in Treating Poisoning

Unlike some other types of rodenticide, SGAR poisoning is difficult to treat because the toxin can remain in the body for a long time and the symptoms may not be apparent until it is too late. This is another reason why they are so dangerous to wildlife—once an animal is poisoned, it may not receive the care it needs in time to survive.

Widespread Use

SGARs are commonly used in both residential and agricultural settings, which increases the risk to wildlife and pets. Many people may use these rodenticides without realizing the potential harm they can cause to the broader environment.

Are there alternatives to SGARs?

Yes!

Please read more about Poison Free Pest Control from Mass Audubon:

“How to Control Rodents Without Rodenticides

The only way to permanently keep rodents out of an indoor space is through a process called integrated pest management—a combined approach of removing food sources, closing access routes, and killing or removing any remaining rodents.  

Exclude Rodents 

Rodents fit through holes as small as a quarter. To keep them out of your space: 

• Seal any holes in roofs, basements, crawlspaces, and walls 

• Use wire mesh extending partially into the ground to block off spaces under porches 

• Seal opening around cables, pipes, and wires where they enter your space 

Remove Food Sources 

Rodents will eat almost anything. To starve them out of your space: 

• Never leave pet food out for prolonged periods 

• If you feed birds, only use small amounts of seed at a time, bring in feeders at night, and pick up fallen seed 

• Harvest all food in gardens quickly 

• Keep garbage cans securely covered 

Target Remaining Rodents 

Without food or access, rodents won’t last long. If you must get rid of remaining rodents quickly, consider non-poison methods:

• Snap-traps: be sure to only use snap traps where they cannot be accessed by children, pets, or other wild animals. 

• Electronic traps: electronic traps instantly and painlessly kill rodents without harming other animals. 

• Rodent contraceptives: Products that reduce rodents’ fertility, reducing their populations gradually over time. 

• CO₂ Traps: These traps immediately and painlessly kill rodents by suffocating them with sudden bursts of CO₂ once they enter traps 

Never use glue traps—they trap rodents without killing them, causing immense suffering, and often capture birds and other animals. For more information, check out these resources from Raptors are the Solution.

Trust Nature 

A single family of barn owls can eat 1,000 to 3,000 rodents in a year. When we poison them, we destroy nature’s pest control.
Predators can control more of our pest issues if we let them

How to Recognize SGARs in Your Community 

Wildlife advocates can easily identify SGARs. Federal law requires pest control professionals to place SGARs within tamper-proof bait boxes, typically made of black plastic and roughly the size of a shoebox. Pest control professionals generally place bait boxes in places with high rat populations, like basements, attics, alleys, or under porches. All bait boxes must be labeled with the type of poison they contain. 

The most common SGARs include: 

• Brodifacoum (Brand names Mouser, Ratak, Talon) 

• Bromadiolone (Brand names Maki Mini Blok, Contrac) 

• Difenacoum (Di-Kill) 

• Difethialone (First Strike, Hombre) 

If you recognize a bait box that contains SGARs in your community, consider discussing the dangers of these poisons to wildlife with the property owner, and the steps they can take to control rodent populations with poison-free methods.”

- https://www.massaudubon.org/take-action/advocate/poison-free-pest-control